1. Field of the Invention
The present invention relates generally to an electromagnetically operated valve assembly for controlling the flow of fluid by modulating the pulse width and particularly to a valve assembly of this type which is improved to increase its durability and its responsibility to intermittance of operating electric current by reducing the preload of a spring and by interposing between an iron core and a movable member a shield nonmagnetic material having a great hardness.
2. Description of the Prior Art
As is well known in the art, since an electromagnetically operated valve assembly of this type is driven at a frequency of several tens Hz for making pulsation of fluid small and is opened and closed extremely many times, it is required to have a severe durability and a satisfactory responsibility. However, conventional electromagnetically operated valve arrangements have not met these requirements and have been usually damaged by opening and closing of about 3.times.10.sup.6 to 5.times.10.sup.7 times in durability.